Me and a friend were running to another friend who was waiting for us in a 2 level house in lumber yard near train tracks. Me and the other guy running froze, he unfroze and turned around to see me drop to ground dead. No zombies around nor any shots fired. Just froze for bout 15 secs and died. Fully geared, armor and all. Clothing wasent damaged. Was able to capture a recording of the event.